Your red snapper is probably fake
The girls sampled 60 different kinds of sushi, then Wong ran them up against the growing library of DNA at the Fish-Barcode of Life. He could get a reading on 57 samples and found that 14 of them were mislabeled. And all the labeling errors went in the seller's favor, making the fish more expensive.
The most mislabeled fish was red snapper: seven of nine samples (77%) were really something else. Most egregiously, some of it was really the endangered Acadian redfish. Their results are no fluke. This spring the Chicago Sun-Times did a great investigation on Chicago sushi and found all 14 of its samples of red snapper were fake, mostly the cheaper tilapia. They say a congressional report found that 37% of fish and 80% of red snapper sold in America is mislabeled. That's consistent with a 2004 University of North Carolina study that found 75% of red snapper was fake.
The mislabeling is an obvious fraud. I'm not worried about the fish connoisseurs who pays extra for some fancy species. If they can't taste the difference, they were wasting their money anyway. I am worried about two other groups of eaters who are totally getting cheated: pregnant women and anyone paying extra to help conserve the world's shrinking fish stocks.
Pregnant women are the biggest worry. They aren't supposed to eat fish that live a long time like shark, mackerel, tilefish or swordfish and only eat a little light tuna because they are the ones that are likely to have more mercury built up in their systems. Mercury causes birth defects. The fish industry likes to play up fish's omega-3 health benefits and say that women just have to avoid certain species. But that's impossible when so much fish is totally mislabeled.
The other group I'm concerned about are the eaters who pay attention to what kinds of fish they should and shouldn't eat for environmental reasons. Here they're paying more not for taste, but to help save fish species, ecosystems and fishing communities. The red snapper wasn't that great of a fish to eat for the environment anyway. The National Marine Fisheries Service rates the red snapper as over-fished and that red snapper fishermen also accidentally catch a lot of sea turtles. The Gulf of Mexico has only 6% of what it needs for a sustainable breeding population. But certainly nobody expected to be eating an endangered fish.
As the DNA tests become more available, I hope more people will be doing them. One company, IdentiGEN Ltd., is even pushing DNA barcode testing as a way to make ensure the identity of pork sold as being as Nature's Premium Brand -- which treats the pigs humanely and doesn't feed them meat or anti-biotics. Geez, with private companies and high school kids using DNA-code testing, maybe some day it will occur to the regulators in charge of food safety to try it.